1. Field
The present invention relates to self-guided aerial vehicles, and more, particularly to non-Global Position System (“GPS”) enabled self-guided aerial vehicles.
2. Related Art
Many modern air-to-ground systems include self-guided aerial vehicles capable of navigating standoff distances to a target. Most of these systems include control surfaces that allow the aerial vehicle to travel or glide through the air to their respective targets. Generally, all of these types of systems are “launch-and-leave” (also known as “fire-and-forget”) type systems that do not require further guidance after launch and are capable of arriving at an intended location without the launcher being in line-of-sight of the location.
Generally, most types of self-guided aerial vehicles guide themselves to a desired location utilizing some combination of sensor technologies that include, for example, inertial measurement units (“IMUs” such as, for example, gyroscopes, altimeters, accelerometers), Global Position System (“GPS”) navigation systems, radar, laser, infrared homing optics, terrain matching, or star-tracking technologies. Of these, GPS-enabled aerial vehicles have become the most common.
Existing GPS navigation systems include NAVSTAR (an acronym derived from either “Navigation Signal Timing and Ranging” or “Navigation Satellite Timing and Ranging”) developed and operated by the United States Air Force and the Global Navigation Satellite System (“GLONASS”) developed by the Soviet Union and presently operated by the Russia Aerospace Defense Forces. Future GPS navigation systems will include global navigation satellite system (“GNSS”) known as GALILEO that is be produced by the European Space Agency (“ESA”) of the European Union (“EU”), the Indian Regional Navigation Satellite System (“IRNSS”) that is being produced by the Indian Space Research Organization (“ISRO”), and Chinese BeiDou Navigation Satellite System being produced by China.
Unfortunately, anti-GPS technologies (such as, for example, GPS spoofing and jamming) are also advancing, creating situations in which a self-guided aerial vehicle may need to pass through contested degraded operation (“CDO”) conditions, which may include either GPS-denied or GPS-degraded environments. Once GPS is denied, the other known navigation technologies, such as IMUs, target-looking imaging sensors (such as, for example, radar, electro-optical, and infrared), and star-tracking technologies may not be capable of providing highly accurate delivery accuracy at the desired location when the time of flight or distance traveled is large because these navigation technologies they either provide mid-course navigation or terminal accuracy. Moreover star-tracking technologies may be limited by ambient conditions (i.e., weather, ambient lighting, etc.), the sensors are expensive, and the processing may be intensive.